Actuator and contact assembly for rotary action switches



April 30, 1968 J. F. DUFFIELD ET AL 3,381,103

ACTUATOR AND CONTACT ASSEMBLY FOR ROTARY ACTION SWITCHES Filed May 12, 1966 3 Sheets-$heet 1 ACTUATOR AND CONTACT ASSEMBLY FOR ROTARY ACTION SWITCHES Filed May 12, 1965 April 1963 J. F. DUFFIELD ET AL 3 Sheets-Sheet 2 q L MN ll. Em m a @f April 30, 1968 J. F. DUFFIELD ET AL 3,381,103

ACTUATOR AND CONTACT ASSEMBLY FOR ROTARY ACTION SWITCHES 5 Sheets-Sheet 3 Filed May 12, 1966 FIG.4

United States Patent 1 Claim. (Ci. zen-156 ABSTRACT 0F THE DISCLOSURE An electrical switch of the push button rotary action type having a novel actuator and contact assembly including a rotatable member, includim a cylindrical cam, having a plurality of alternate elevations and depressions spaced around the operable region thereof. A pawl, associated with the push button, is provided to cause selective rotation of the rotatable member in discrete movements each substantially equal to the spacing between the elevations and depressions thereof. The electrical switch assembly is also provided with a movable contact having a contact region and a cam follower region for selective engagement with the said elevations. There is also provided a fixed contact having its own contact region which is selectively engageable with the contact region of the movable contact. The fixed contact also includes restraining means which abuts the rotatable member to substantially inhibit the movement thereof in a direction away from the cam follower of the movable contact.

This invention relates to rotary action switches and in particular rotary action switches actuated by successive depressions of a manually operated button. Such switches are restricted to light current alternating voltage systems although other applications would appear to be applicable.

Numerous designs of rotary action switches will be found in the prior art but with the ever present desire to improve reliability of such switches and to reduce the cost of manufacture such prior known switches are not found to be economically feasible to produce or reliable in operation.

Examples of prior known rotary action switches will be found in the following United States Patents 2,820,113, 2,928,920, 2,933,578, 2,933,579, 2,950,372, 2,965,737, 2,967,222, 2,991,344, 3,073,933, and 3,084,239. A careful examination of the prior known devices, as exemplified by the aforementioned patents, shows that they all suffer from all or some of the following disadvantages. The necessity of providing an associated insulated body member having two or more separable portions each portion of which assists in locating the rotary member or other element of the mechanism. Such devices have also required fairly accurate positioning of the bearings for the rotating member and it has been necessary to provide the latter with fairly accurate trunnions or journals. Some of the prior known devices have required additional non-return or locking pawl elements to insure that the rotary member is subjected only to a unidirectional movement. The most important disadvantage, a disadvantage shared by all the known devices, is that the spacing between the associated stationary and moving contacts has had to be made fairly large in order to accommodate manufacturing tolerances. Needless to say the spacing of the contacts, particularly when separated, has led to the overall size of the switch as a whole being unnecessarily large and such spacing has prevented the miniaturization of such switches. Again, such prior known switches have been difiicult to assemble and in many instances it has not been possible to examine the operation of the switch before the cover and or yoke is placed in its final position.

In overcoming the disadvantages of prior known switches of the rotary action type, we propose to provide a ratchet mechanism having an associated cam thereon wherein the ratchet mechanism is loosely retained in a bearing and wherein the ratchet member assumes a position which is established by one of the contacts in such a manner that the selected contact will hold the ratchet member in such a manner that the precise position of the latter, within practical limits, may move without sub stantially effecting the spacing between the fixed contact and the associated moving contact. The principle of the invention not only enables the relative positions of the fixed and moving contacts to be established prior to assembly of the switch and without subsequent adjustment when once assembled into the switch but also enables the novel switch to perform reliably over a long period of time and also enables the switch to be manufactured at a much lower price in spite of its enhanced reliability and susceptibility to miniaturization.

It is an aspect of one feature of the invention to provide a rotary switch wherein theactive members may be adjusted to provide desired spacing between fixed and stationary contacts prior to assembly into the switch.

In accordance with the foregoing aspect of the invention, the invention comprises an actuator and contact assembly for use in rotary action switches comprising: (i) a rotatable member including a cylindrical cam having a plurality of alternate elevations and depressions spaced around the operable region thereof, (ii) means for selectively rotating item (i) in discrete movements each sub stantially equal to the spacing between said elevations and depressions, (iii) a movable contact member including a first contact region thereon and a cam follower region for selective engagement with said elevations, and (iv) a fixed contact member including a second contact region thereon, said second contact region being selectively engageable with said first contact region in response to the engagement of said cam follower with said cam, said fixed contact member further including restraining means abutting said rotatable member and substantially inhibiting movement of said rotatable member in a direction away from said cam follower.

The invention will now be described with reference to the accompanied drawings in which:

FIG. 1 shows the relative positions of a ratchet wheel and cam wheel assembly, a fixed contact and a moving contact.

FIG. 2 is a plan view of the active portion of a two-pole switch incorporating the ratchet wheel and cam assembly shown in FIG. 1.

FIG. 3 is a side view of a complete switch assembly, shown partly in section.

FIG. 4 is an end view taken in section along the lines 4-4 in FIG. 3, and

FIG. 5 is a side view taken in 55 of FIG. 4.

Referring now to FIG. 1 there is and cam assembly, forming a rotatory member generally indicated at 1, and consisting of a pair of trunnions, one of which is indicated at 11, a ratchet wheel indicated at 12 and a cam 13. As will be described hereinafter the trunnions 11 are received, loosely, in suitable apertures in an associated body member. A fixed contact member, generally indicated at 2, includes a straight portion 21 and a substantially semi-circular portion 22 which portion is adapted to partly embrace an outer periphery formed on the ratchet wheel and cam assembly 1. The fixed contact member 2 is provided with a contact pad 23 having a substantially flat surface thereon. A moving contact section along the lines shown a ratchet wheel member, generally indicated at 3 consists of a straight portion 31, a cam follower portion 32 and an extension 33 upon which is mounted a moving contact pad 34 having a substantially convex surface thereon. The cam follower portion 32 is disposed adjacent the cam 13 and resiliently urged there against by the inherent resiliency of the material from which the moving contact member is made. This material may of course be brass, bronze or other suitable contact material.

The substantially semi-circular portion 22 of the fixed contact member 2, the nominal position of the moving tcontact member 3 and the proportions of the cam follower portion 32 are so chosen that upon rotation of the ratchet wheel and cam assembly, by means to be dis cussed, the moving contact pad 34 moves alternately into and out of engagement with the fixed contact pad 23. It will be apparent from FIG. 1 that the ratchet wheel and cam rotatory assembly 1 may be received into the associated body member with a fairly large degree of freedom. In spite of this, the space between the fixed contact pad 23 and the moving contact pad 34 is entirely under the control of the relative positions of the rotatory member 1 and the cam follower 32 and these relative positions are established by the portion 22 abutting the rotatory member 1. Such positions may be established prior to assembly of the above-described components into the switch proper and such spacing may provide a much smaller gap between the contacts when the contacts are separated.

Referring now to FIG. 2 there is shown a plan view of a two-pole version of the single pole embodiment shown in FIG. 1. It is seen in FIG. 2 that the ratchet wheel 12 is common to a pair of cams 13. According to the angular disposition of the high and low points on the respective cam members 3 it will be possible to provide a double pole single throw switch or single pole double throw switch. In either case the ratchet wheel will be rotated by one tooth for each depression of the associated button to be described. The number of teeth on the ratchet wheel will in general be numerically equal to twice the number of high points or low points on the cam 13.

Referring now to FIGS. 3, 4 and 5 there is shown the present invention applied to a base 4 for installation in a standard receptacle box by means of a standard yoke 5 and an insulator 6. It will be seen that the portion 21 of fixed contact 2 is extended to form a U-shaped terminal element as at 24 and that portion 31 of moving contact 3 is extended as at 35 to form a further U- shaped terminal member. The two terminal members form no part of the present invention.

FIGS. 3, 4 and 5 each show a manually operable button 7 having a pair of trunnions at one end thereof, one trunnion of which is indicated at 71. At the remote end of the button 7 there is shown an extension 72 around which is disposed a pawl 8 to be described hereinafter. The button 7 may be of solid material, or as shown particularly in FIG. 5 may be of hollow configuration and of translucent material and adapted to house a neon lamp 8 and a resistor 9 in a manner well known to those skilled in the art. The ratchet wheel and cam rotatory assembly 1 is loosely received in a pair of slots 41 and retained therein by the semi-circular portion 22 of the fixed contact member 2, the ratchet and cam assembly 1 is then in a proper position for engagement by the cam follower portion 32.

The pawl 8 attached to the button 7 is dis-posed to. rotate the ratchet and cam assembly 1 by one tooth of ratchet 1 for each depression of the button 7, a compression return spring 9 is positioned between the underside of the pawl 8 and a suitable recess 41 in the base 4.

It will be seen that the assembly of the switch as a whole entails no more than placing into osition moving contact member 3 the ratchet and cam assembly 1, the fixed contact member 2, spring 9 and the button 7 comeLO plete with its pawl 8. It will be further noted that the portions 24 of the fixed contact member 2 and the portions 35 of the moving contact member 3 are gether at curved portions 25 and 36 respectively. These curved portions 25 and 36 bear against the insulator 6 which in turn is held in position by the yoke 5. Thus the fixed contact member 2, the moving contact member 3 and the ratchet and cam assembly 1 are all held in position once the insulator and yoke are positioned in the final locations.

The novel switch mechanism herein disclosed is of extreme simplicity and capable of being functionally checked before the button 7 is placed in position. It is only necessary that the assembler of the switch place a finger on the curved portions 25 and 36 respectively of the fixed contact member 2 and moving contact member 3, in order to check that the contact pads 23 and 34 make proper contact and properly separate during movement, by one tooth of the ratchet wheel 12.

It will be appreciated that the length of the cam follower 32, the respective thicknesses of the fixed and moving contacts 23 and 34 respectively and the throw of the cam 13 will be dimensionally established during the production of each. Thus, the configuration of the "curved portion 22 of the fixed contact member 2 may be finally set after taking the aforementioned dimensions into account. Thus the novel mean-s of maintaining the ratchet and cam rotatory member 1 in proper dimensional relationship with the fixed contact member 2 and the moving contact member 3 permits their interrelationship to be kept within strict limits. It is imperative in *an AC. switch that whilst a minimum ga for break be established, the means employed for such establishment must not impair movement of a spring contact, such as element 3, otherwise this would tend to interfere with its freedom to make contact at the required pressure with the fixed contact 2. The present invention ensures the simplest possible method of manufacture, a minimal number of components and assembly of which provides a switch whilst thoroughly reliable is inexpensive to manufacture and of long life. Further, in reducing the number of elements used in the disclosed switch by forming the bearings integrally with the stationary contact the operating force required to directly open the contacts is equally shared between the stationary contact 2 and moving contact 3 thus imparting a constant predetermined deflection of the moving contact when switching oli. It follows from this that whilst a constant deflection for break is maintained throughout the life of the device that the conditions of make are equally well maintained thus ensuring that the contact pressure is never impaired.

It will be obvious to those skilled in the art that the novel switch mechanism herein described can be applied to single throw switches, single pole double throw switches, double throw single pole switches or double throw double pole switches. Again, whilst the mechanism has been shown in an embodiment of a manually operable switch it is obvious that the mechanism can be applied to a mechanically operated depressing means applied to any of the above-mentioned types of switches. However, other embodiments of the invention falling within the terms of the appended claim will appear to those skilled in the art.

We claim:

1. An actuator and contact assembly for use in rotary action switches comprising:

(i) a rotatable member including a cylindrical cam having a plurality of alternate elevations and deipressions spaced around the operable region thereof,

(ii) means for selectively rotating item (i) in discrete movements each substantially equal to the spacing between said elevations and depressions,

joined to- (iii) a movable conta'ct member including a first contact region thereon and a cam follower region for selective engagement with said elev'ations, and,

(iv) a fixed contact member including a second contact region thereon, said second contact region being selectively engageable with said first contact region in response to the engagement of said cam follower with said cam, said fixed contact member further including restraining means abutting said rotatable member and substantially inhibiting movement of 6 References Cited UNITED STATES PATENTS 2,823,278 2/1958 Carlson et a1. n 200156 X 3,084,239 4/1963 Horvath et a1 200156 FOREIGN PATENTS 218,599 3/ 1961 Austria,

ROBERT K. SCHAEFER, Primary Examiner.

said rotatable member in a direction away from said 10 H BURKS Assistant Examiner' earn follower. 

